Process of manufacturing compound fertilizers



Patented Sept. 1931 UNITED STATES PATENT OFFICE ERLING JOHNSON, OF ODDA,NORWAY, ASSIGNOR TO THE FIRM: m n SMELTEVERK A/S., or ODDA, NORWAYPBQCESS OF MANUFACTURING COMPOUND FERTILIZERS No Drawing. Originalapplication filed September 9, 1929, Serial No. 391,507, and in NorwayNovember 24,

1928. Divided and this application filed December 26, 1930. Serial No.505,004=.-;--

sion from my pending patent application Ser.

No. 391,507 relates to a process for producing compound fertilizers fromsaid mother liquor.

According to my present invention I use this mother liquor for treatingphosphate rock in the presence of potassium sulphate.

The free phosphoric acid and the free nitirc acid of the mother liquorwill convert the phosphate rock into mono-calcium phosphate and calciumnitrate. The calcium present is converted into gypsum by the potassiumsulphate. T he entire reaction product is dried and constitutes aconcentrated compound fertilizer high in watersoluble phosphoric acidand in potash, but relatively low in nitrogen.

To increase the content of nitrogen so as to form a universal fertilizerwith a Well balanced ratio of P O zK ozN a suitable quantity of urea maybe added to the mother liquor or admixed to the reaction product.

The manner of carrying out my process and the composition of thefertilizer products obtained may by Way of example be illustrated by thefollowing data.

Example 1.100 parts of mother liquor resulting from the processdescribed in my patent application Ser. No. 391,5Q6 and containing percent phosphoric acid (P 0 4.6 per cent CaO as nitrate of calcium.equivalent to 2.3 per cent nitrogen, and further {2 per cent nitrogen inthe shape of nitric acid, were treated with 40 parts of phosphate rockof 36 per cent in presence of 40 parts finely ground potassium sulphate.The reaction proceeds under evolution of heat; By appropriate supply ofsome additional heat the reaction is completed in a rather short time. The mass is maintained at 70 C. until the product is sufliciently dry.Drying under vacuum may of course also be used.

150 parts of product were obtained with a content of 30.0 percentphosphoric acid- (the by far prevailing portion-being watersolublc),14.7 per cent potashv and 4.33 per cent nitrate nitrogen. E'zrample2.When 80 parts of the material produced according to Example 1 aremixed with 20 parts of urea, a dry product is obtained which shows thefollowing composition Relative ratio Some 24 per cent of phosphoric acid2 12 per cent of potash l 12 per cent of nitrogen 1 Of the nitrogen 3.5per cent are nitrate nitrogen and 8.5 per cent urea nitrogen' Theproducts obtained have excellent; physical properties. Thov are verystorable and easy to spread. My process had obvious merits over previousproposcd'processes for preparing compound fertilizers by treatingphosphate rock with nitric acid in the presence of potassium sulphate.

The mother liquor used in my process is practically a solution ofphosphoric acid and contains only minor quantities of calcium. Thereforemy process leads to far more concentrated fertilizers than it waspossible to obtain according to said previous proposals.

As regards the use of urea my process has likewise great merits overpreviously proposed manners of working. 4

It has been suggested to convert phosphate rock by means of nil rie acidinto a solid roduct of mono-calcilun phosphate and ca cium 'nitratel'andto add urea to the product in tains only very little calcium nitrate, asthis substance has been previously removed by the foregoingcrystallization. The amount of urea which is required for combinationwith the calcium nitrate present is a very moderate one, and the processallows to prepare a dry storable compound fertilizer with a wellbalancedratio P 0 N.

It is understood that the carrying out of my process is not limited tothe ratio of components above mentioned. For example, the quantity ofphosphate rock may be varied in accordance with the composition of themother liquor, particularly with regard to the content of free nitricacid in the mother liquor. And likewise the amount of potassium sulphateand urea added may vary considerably according to the percentage ofpotash and nitrogen desired in the finished product.

I claim:

1. Process of manufacturing compound fertilizers from the solution whichis obtained by treating phosphate rock and similar phosphate materialwith nitric acid and crystallizing the greater part of thecalciumnitrate contained in said solution, comprising adding mineralphosphates and potassium sulphate to the mother liquor from thecrystallization of calcium nitrate and removing the surplus of water.

2. Process of manufacturing compound fertilizers from the solution whichis obtained by treating phosphate rock and similar phosphate materialwith nitric acid and crystallizing the greater part of the calciumnitrate contained in said solution, comprising adding mineral phosphatesand potassium sulphate and urea to the mother liquor from the calciumnitrate crystals and removing the surplus of water.

3. Process of manufacturing compound fertilizers from the solution whichis obtained by treating phosphate rock and similar phosphate materialwith nitric acid and crystallizing the greater part of the calciumnitrate contained in said solution, comprising adding mineral phosphatesand potassium sulphate to the mother liquor from the calcium nitratecrystals, removing the surplus of water and admixing urea to the productso obtained.

In testimon that I claim the foregoing as my invention have signed myname.

ERLING JOHNSON.

